Insulin action will be studied in terms of 4 interrelated areas including 1) the isolation, purification to homogeneity and structure determination of several novel mediators of insulin action; 2) the separate high affinity binding and bioactivity domains of the insulin molecule; 3) the mechanism of the enhanced insulin receptor phosphorylation in the presence of the hormone and its possible relationship to mediator formation and 4) studies on the biochemical mechanism(s) of insulin resistance in human cells of diabetic patients.